The present invention relates to a circular pole piece included in a magnetic circuit for magnetic resonance imaging (MRI), a method of manufacturing a laminate block employed in the circular pole piece, and an MRI system employing the circular pole piece.
In the past, a circular pole piece included in a magnetic circuit for MRI has been shaped substantially circularly as a whole by arranging laminate blocks each of which has square or rectangular soft magnetic material tiles or heteromorphic soft magnetic material tiles, each of which is used to fill a gap among adjoining square or rectangular tiles, layered (see, for example, FIG. 1 in Patent Document 1). Otherwise, the circular pole piece has been shaped substantially circularly as a whole by arranging laminate blocks, each of which has trapezoidal or annularly sectoral soft magnetic material tiles layered, in the form of multiple concentric rings (see, for example, FIG. 21 in the Patent Document 1).
[Patent Document 1]
Japanese Unexamined Patent Publication No. 2000-200716
Laminate blocks each having square or rectangular soft magnetic material tiles or heteromorphic soft magnetic material tiles, each of which is used to fill a gap among adjoining square or rectangular tiles, layered may be arranged to form a substantially circular pole piece. In this case, since the heteromorphic soft magnetic material tiles must be arranged, the work is complex and the cost of the pole piece is high.
On the other hand, laminate blocks each having trapezoidal or annularly sectoral soft magnetic material tiles layered may be arranged in the form of multiple concentric rings in order to produce a substantially circular pole piece. In this case, there is a gap between adjoining rings or adjoining laminate blocks included in one ring. Moreover, in order to eliminate such a gap, trapezoidal or annularly sectoral soft magnetic material tiles of different sizes must be arranged. This leads to complex work and a high cost.